Synchronizing mechanism for freepiston engine compressor



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Sept. 20, 1960 E. A. wAcHsMUTH 2,953,294

SYNCHRQNIZING MECHANISM FOR FREE-PISTON ENGINE COMPRESSOR I 2sheets-sheet 1 Filed Dec. 13, '1956 Sept. 2D, 1960 l; A. wAcHsMuTH2,953,294

' SYNOHRONIZINO MEOHANISM FOR EREE-PISTON ENGINE COMPRESSOR Filed Dec.13, 1956 2 Sheets-Sheet 2 .synchronizing .fsck .and ciicct Plcrfccsbilanci United States Patent sYNcHRoNIzING` MECHANISM Fon FREE- PISTONENGINE COMPRESSOR Erich A. Wachsrnuth, Michigan City, Ind., assigner to'.Ioy Manufacturing Company, Pittsburgh, Pa., a cor- This inventionrelates to free-piston n lotor-compresrsors, and more particularly tosynchronizing mechanism for such devices of the character in which thereare two power cylinders arranged parallel with each other and with theircentral portions cut by a common plane perpendicular to their axes;there are two pairs of opposed motor pistons adapted to reciprocate insaid cylinders respectively, each motor piston having iiJed to its outerend a compressor piston; there are two pairs of compressor cylinderseach pair having between .its cylinders one of the iirst mentionedcylinders and adapted to receive compressor pistons ixed to the outerends of lthe pistons of the rst mentioned cylinders respectively;thereris means for connecting one motor piston of one pair to thecorresponding motor piston of the 'other pair to cause them to movesimultaneously in mutually opposite directions, and means for connectingthe other motor piston of said one pair with the corresponding motorpiston of said other pair to cause them to move simultaneously inmutually opposite directions, and means` is provided for causing thepistons of both pairs to move in synchronism with each other. I i I l ci A free-piston motor-compressor of the type mentioned is disclosed inmy application Serial No. 272.019, tiled February 18, 1952, now PatentNo. 2,775,398, for Free'- PistonCompressor; but the mechanism of saidapplication is much wider than that of this ap ication andthesynchronizing mechanism is not nnngcd 'onisisic tho inschinc finnioansi. so is loss nccossiblc- YThjs now Inconsiniin of thc Prcscntinvcntion. is snin1l,.cof1npact' and ple, yet avoids interferences.lbetween; the synchronizing incchanisins and pans. associarsi with. th..cylinders, 'and Rosscsscs tholcinornstic ,/i'nfncv tlcf two4svncnronizod piston systems obey exactly the sanielaw ofspee lFtoincontain of its aspects fhcinvontio is. nlsosdaptcd to opnoscd pistoncngincs, Pcf nsf disiingnishcd." from motor-compressors., ansi fromother nsnccts relatos/1ro improved arrangements c for maintainingdesired, relative inovcnicnts in dcvicos-'oiihci inotors oinioio-compressors-.constituting basically ono 'longitudinal half: of s.inoton or of s, motors-compressor ot. fhc c'isrscfcrV sb'ov mqnipned i....n

ln a desirable embodiment,of` the invention asY applied to amotor-compressor or opposed pistonengine the'synchronizing mechanism mayconsist of two A` equal Vgear pinions each connected with one of tworocking'shafts that cause piston structures traveling in parallelv pathsbetweenv corresponding` limits to move opposite'ly `to each other, and ailoating diagonally arranged gear rack which mates with the. twopinions,' and the inertia forces of the floating gear rack may bebalanced by tWO vScParately floating countcrwcghts-also goariacks., cashOno. @5.1.1.5 wtnono ofihc pinions., howcvoi on diainciricslly onnoscdsides from .snc synchronizing rack init 'sslci with'A thc latter,wherebythe counterweights'move opposite to'but always withthe sameinstantaneous angular Speed as' t latter.E

2,953,294 Patented Sept. 2 0, 19,6()F

I t is an object of the present invention to provide an improvedapparatus. for synchronizing theA movements of anv apparatus of theopposed piston type. It is a further object of the invention to providean improved apparatusa for synchronizing a motor-compressor of the`double, opposed' piston type. It is a further object of the v`inve'n'tion to provide improved, synchronizing apparatus for machinessuch asopposed piston motors and motor# compressorsfhaving improvedycounterbalancing means. It is still another object of the invention toprovidefaii improved double opposed piston engine. Still another objectis to provide an improved double opposedA piston motor-compressor.Another object is to provide aninjl Piovod. connicrbslonccd,synchronizing mechanism; a further object is to provide an improved?connecting arrangement between parallel, oppositely moving piston andconnecting rocker;V Other objects and advantages of the invention willhereinafter appear.` VIrnthe accompanying drawings, in which, forpurposes of illustrati n, oneillustrative embodiment of the invefn'ltiqn ispshownz. Fig. 1 is a diagrammatic view in central longitudinalhorizontal section, with parts in elevation, througlr'amotor-eompressor/in the invention is incorporated, the section beingtaken "on thel plane of the line 1-4-1 of Fig. 2', and having shown withitcertain parts 'not illustrated in 2. 'A c I i Y i i' NW- Fig. 2 is avertical transverse section on an enlarged scale'ion thev ,roken line2.-2 of Fig. l, showing'details ofconstruction.v Fig. 3 is a horizontalsection, on the same scale as-Fig.

l, orf'the plane Vof the line 33 VofV Fig. 2 illustrating dctails ofthensynch'ronizing mechanism and its associated counterbalan'cingmechanism. i Y Before proceeding lto the specication, it is to be notedthatv afree-pis'ton motor-'compressor includes as a part thereof afree-piston engine or motor and, accordingly, although/there arepresented` claims to a freep-p'iston motor iler se;A there isfnonecessity for illustrating anentirely independent freefpiston motor tosupport the claims.V vReferring r'st to Fig. 1,'itv will be noted thatmotor cylinders 1f" arenprovided. yThe `0f these cylinders are atleastsubstantially parallel and the cylinders "fare supported by vaffrz'ivme-l-"X The ymotor Cylinders 1 1 have l1 ersr wzwin which thereVare'reciprocableY in couriterstroke (opposed) relatiori'to each othertwopistcns 4, 5

and'4', 5"," control thescayegingf slots'6, 6' e b ust slots:` 7,' 7.V`The four pistons are'formed as' ifferential pistons andI are coupledlin pairs ('4 coupled with fand 5 coupledV with `5"), each pairby adouble; armedfroclger, or centrally pivoted lever, 8, 9, the first pair`by thc rocker and the 'second by the'rocker 9, so that' the outwardtravel (working stroke)"of the'pi's'i das assessed with the cylinderreorfespngis with "the inward"` (compression) stroleof thecorrespondirig'pisl tons of, tlieeylinder `1, and vice versa. VThe twodoublea'rnied rockers'f y*and 9'` arepivoted respectively at 1Q and"11,' The piston structures 4,'5 and 4" and 5" are hollowwand have slotsl'through their peripherall'walls through which slots the rockers Sands9 extend. Wfareblilt ofthe necessary strength, butha've their7tVdistribiited` in sucha 'manner'as to allow the necesry range ofswingen their'aicswithout having`"the slots .13V unnecessarily enlarged.There is a connection between each `of("the"s .veral `vpistonstructures,v 4, S'and 4", 5' `witharrendV o fvv a rocker, and VtheseVconnections are in the foi-'m cf connecting rods A1'5 -pivotally con#necte-d at Y1,6fto the adjacent A e'ndofa rocker AarmA andpivotallyconnvected at 157 tov aV piston construction. The 'rockersarel'ri/gidly mounted on (keyed to) oscillating '18`and`519, andtheseshaftsv are journaledfi'n ap' i propriate bearings, herein shown asrollerbe'a'rings 20;

21 respectively, in end plates 22 and 23, closing openings in the topand bottom of the frame F.

Compressor cylinders 24, 25 and 24', 2S are disposed coaxial with themotorV cylinders 1, 1', and are open at their ends toward the motorcylinders, but closed at their outer ends by cylindrical heads 26, 27and 26', 27', which carry the suction and discharge valves 28, 29.I'here are two receivers 30 respectively receiving compressed uid fromthe discharge valves 29 associated with cylinders 24, 25 and from thoseassociated with the cylinders 24', 25'. The compressor cylinders areprovided with liners which are distinguished from the cylinders properin each case by the addition of L to the individual cylinder members.

It will be noted that the rockers 8, 9 are comprised of a central hubportion 32 and at diametrically opposite sides of the hub portion spacedarms 33, 34 and 33', 34. In the space 35 between the arms there issecured to the hub portion a counterweight 36 which is provided to makethe weight at opposite sides of a plane which includes the axes of thepivot connections 16 and the axis (or 11) equal, whereby the rockers perse are balanced statically and dynamically with respect to the pivotaxes 10 and 11. It may also be noted that the trunklike portions 38connecting the motor pistons (4, 4, 5, 5') with the compressor pistonswhich are numbered 39, 39', 40, 40 are slabbed off at their sides sothat there are parallel vertical surfaces at such opposite sides (seeFig. 2).

The connecting rods engage, as shown in Fig. 2, with pins 43 which aresuitably journaled in the parallel arms 33 and 34.

To maintain the proper synchronized relation between the motor pistonsin the cylinder 1 and those in the cylinder 1', mechanism as follows isprovided.

The shafts 19 each have reduced portions 44, herein shown as tapered,and upon these reduced portions there are mounted elements 45 which havearcuate toothed portions at diametrically opposite sides thereof, theseelements having, as herein illustrated, the form of circular pinions 46with appropriate teeth 47 extending completely around their peripheries,although this is not strictly necessary. The pinions 46 have extendingbetween one side of one of them and the diametrically opposite side ofthe other a rodlike structure 48 having at each of its opposite ends arack portion 49 meshing with one of said pinions 46. The rodlikestructure 4S extends obliquely to the plane which includes the axes 10,11, and extends from below such plane at one end, through such plane,and above it at the other end. The rodlike structure 48 is hollow, andthe straight rack portions 49 at its opposite ends are formed hollow asat 50 to reduce the overall weight of the rodlike structure 48. Therodlike structure receives shank portions 51 of the rack portions 49 inits opposite ends, and is carefully balanced so that in the mid-positionof the rockers half of the rodlike structure is at one side and half atthe other of a vertical plane midway between the axes 10 and 11 andperpendicular to the cylinder axes. The pinions and the rodlikestructure are suitably housed, the pinions and the reciprocating rackportions being housed in gear boxes 52, and the portion of the rodlikestructure between the gear boxes being enclosed in a suitable tubularhousing or sheath structure 53.

The structure described in the preceding paragraph is effective toprovide a synchronous but counter directed movement of the rocker armsunder exactly similar angular speed arrangements. The rack portions 49are borne by -two rack guides 54. The inertia force of the straightreciprocating rack portions 49 and connecting rod portion 55 of therodlike structure 48 is balanced by two separate oating counterweights57, also gear racks, each one meshing with one of the pinions 46, but ondiametrically opposite sides of the synchronizing rack structure andarranged parallel to it. This makes them move opposite to, but alwayswith the same instantaneous angu- 2,953,294, f i Y lar speed as thesynchronizing rack structure, and allows balancing the latter perfectly.The balancing counterweights also have guides, 58, in the gear housingsand each is of the same mass as the adjacent synchronizing rack and thathalf of the reciprocating rodlike structure which is nearer to theparticular counterweight.

It will be observed that the synchronizing mechanism is outside (above)the machine frame F, and above the top bearings 20 of the rocker shafts18, 19, whereby it is easily accessible. The arrangement describedpermits locating the cylinders 1 and 1 as close together as ismechanically possible without sacriiice of exhaust duct area orinterference between the exhaust ducts and synchronizing rack. The mainadvantage of the new synchronizing mechanism, in addition to itssimplicity and the small space it requires, is the kinematic virtue thatthe two synchronized piston systems obey exactly the same law of speed.

While there is in this application specifically described one form whichthe invention may assume in practice, it will be understood that thisform of the same is shown for purposes of illustration and that theinvention may be modified and embodied in various other forms withoutdeparting from its spirit or the scope of the appended claims.

What I claim is:

l. An apparatus of the type described comprising, in combination, atleast two power cylinders, at least two pairsv of opposed pistonsadap-ted to reciprocate in said cylinders respectively, yand connectingmeans between the pistons of said two pairs for synchronizing theoutward strokes of one pair with the inward strokes of the other pair,said connecting means including rockers s-wingable on xed axes in planesperpendicular to the axes of said cylinders, ktoothed circular elementsxed to said rockers for oscillation on the axes of said rockers, andmeans including an intermediate element having engagement with saidtoothed circular elements for connecting said toothed circular elementsfor oscillation equiangularly but in opposite directions, andcounterweights engaging with said toothed circular elements at theopposite sides of the latter from the engagements of said intermediateelement with said toothed circular elements.

2. An apparatus as set forth in claim l in which the intermediateelement has its engagements with said toothed circular elements at theopposite sides of its opposite ends.

3. -An apparatus as defined in claim 2 in which each counterweight is ofa mass equal to one-half the mass of said intermediate element.

t4. An apparatus as dened in claim l in which each counterweight isequal in mass to the adjacent half of said intermediate element.

5. An apparatus as defined in claim l in which the mesh lines of saidintermediate element and of said counterweights with said toothedcircular elements are equally spaced from the axes of said rockers.

6. An apparatus of the type described comprising, in combination, atleast two power cylinders arranged with their axes parallel, `at leasttwo pairs of opposed pistons one pair reciprocable in one of said powercylinders and the other pair in the other of said power cylinders, andconnecting means between the pistons of said two pairs for synchronizingthe outward strokes of one pair with the inward strokes of the otherpair, said connecting means including rockers swingable on xed axes inplanes perpendicular to the axes of said cylinders, elements fixed withrespect to said rockers for oscillation on the axes of said rockers andeach having arcuately arranged toothed portions of like pitch radius andat opposite sides of its center, and means for connecting said elementsfor oscillation equiangularly but in opposite directions.

7. An apparatus of the type defined in claim 6in which said means forconnecting said elements for oscillation equiangularly but in oppositedirections includes 1a conhectingelement extending 1obliquelyt'o a planeincluding the axes of said rockers.

8. In an internal combustion, free-piston motor-compressor, incombination, coaxial motor and compressor cylinders respectivelycontaining motor and compressor pistons which form a pair, other coaxialmotor and compressor cylinders containing other motor land compressorpistons which form another pair, said iirst mentioned motor andcompressor cylinders arranged with their axes parallel to the axes ofsaid second mentioned motor and compressor cylinders, and means vforconnecting the piston pairs contained in said first and second mentionedcoaxial motor and compressor cylinders -to cause them to move incounterstroke relation to each other including a -lever pivotable uponya -xed axis vbetween the cylinders in which said corresponding pistonpairs are contained, said axis being disposed between the ends of saidcylinders and said lever having its opposite ends connected byconnecting rods with said piston pairs a-t points between the oppositeends of each of the latter.

9. A motor-compressor as defined in claim 8, in which lsaid piston pairsIare hollow and having said connecting rods in their interiors. l

10. An apparatus of the type described comprising, in combination, atleast two power cylinders -arranged with their axes parallel, at leasttwo pairs 'of opposed pistons one pair reciprocable in one of saidcylinders and the other pair in the other of said power cylinders,connecting means between the pistons of said two pairs for synchronizing the outward strokes o-f one pair with the inward strokes of theother pair, said connecting means including rockers swingable on fixedaxes in planes perpendicular to the axes of said cylinders, elementsfixed with respect -to said rockers forosciliation on the axes of saidrockers and each Ihaving -arcuately arranged toothed portions of likepitch radius at the opposite sides of its center, an element extendingobliquely toa plane including the axes of said rockers and cont-actingone of said iirst mentioned elements at one side of its center andtheother `at 'the other 'side of its center, and counterweights coactingwith the other arcuately arranged toothed 'portions of each of said irstmentioned elements.

11. An apparatus of the type described comprising, in combination, atleast two power cylinders arranged with their axes panallel, at leasttwo pairs of opposed pistons one pair reciprocable in one of said powercylinders and the other pair in the other of said power cylinders,connecting means between the pistons of said two pairs for synchronizingthe outward strokes of one pair with the inward strokes of the otherpair, said connecting means including rockers swingable on xed axes inplanes perpendicular to the axes of said cylinders, elements fixed withrespect to said rockers for oscillation on said axes of said rockers andeach having arcuately arranged toothed portions of like pi-tch radiuslat opposite sides of its center and a -bar having teeth on one side ofone end thereof and teeth on the other side of the other end thereof,said teeth simultaneously engaging arcuately arranged toothed portionson said elements, and means for counterbalancing the weight of said barincluding toothed counterweights engaging the other arcuately arrangedtoothed portions on said elements.

l2. A motor-compressor of the type described comprising, in combination,two power cylinders disposed side by side and each having at each of itsopposite ends a compressor cylinder, two pairs of opposed motor pistons,one pair reciprocable in each of said power cylinders, a compressorpiston movable with each motor piston and reciproca'ble in a compressorcylinder, two levers pivoted on xed axes and each operatively yconnectedat one end with a motor piston and a compressor piston, means arrangedwholly between the most widely spaced points in said compressorcylinders for connecting said levers to swing mutually oppositely withrespect to each other, in synchronism, said last mentioned meanscomprising arcuately disposed teeth associated with `each yof -saidlevers and arranged in arcs at opposite `'sides of the pivots of saidlevers and a bar having rack Yportions adjacent its opposite endscoacting with the said arcuately disposed teeth at opposite sides ofsaid axes, and counterweights cooperating with the remaining arcuatelydisposed teeth.

` 13. Amotor-compres'sor of the type described, comprising, incombination, two power cylinders disposed side by side and each havingat each of its opposite ends a compressor cylinder, two pairs of opposed'motor pistons, one pair reciprocable in each of said power cylinders, acompressor piston movable with each 'motor piston and reciprocable in acompressor cylinder, two levers pivoted on iixed axes and each`operatively connectedV at one end with a motor piston and a compressorpiston, and means arranged wholly between the most widely spaced pointsin said compressor cylinders for connecting said levers to swingmutually .oppositely `with respect to each other, in synchronism, saidlast mentioned means comprising arcuately arranged sets of teeth one atone side of said fixed axes and the other at the other side of saidiixed axes and a rod having rack portions cooperating with saidarcuately arranged sets V,of teeth, there being counterweight means atthe opposite side of the axis at one side off which one of saidarcuately arranged sets of teeth is disposed and also at the oppositeside of the axis at the other side of which the other 'set of arcuatelydisposed sets of teeth is disposed.

14. A motor-compressor of the type described Vcomprising, incombination, two power cylinders arranged parallel with each other andwith their central portions cut by a common .plane perpendicular totheiraxes, two pairs of opposed motor pistons adapted to reciprocate insaid cylinders respectively, each motor piston having xed to its outerend a compressor piston,'tWo'-pair s of compressor cylinders each pairhaving between its cylinders one of the rst mentioned cylinders andadapted to receive the compressor kpistons 'fixed to the outer ends ofthe pistons of the first mentioned cylinders respectively, meansincluding an Aoscillating rocker for `,connecting one motor piston ofone pair to the corresponding motor piston of the other pair to causethem to move simultaneously in mutually opposite directions, meansincluding an oscillating rocker for connecting the other motor piston ofsaid one pair with the corresponding motor piston of said other pair tocause them to move simultaneously in mutually opposite directions, meansincluding a rack bar having rack portions and oscillating toothedsegments for maintaining movement of said rockers in synchronism, andmeans including other rack bars and oscillating toothed segments forcounter-b-alancing said rst mentioned rack bar.

15. A motor-compressor of the type described comprising, in combination,first aligned motor and cornpressor cylinders, second aligned motor andcompressor cylinders arranged parallel to the first cylinders, a pistonstructure including motor and compressor pistons reciprocable in saidrst motor and compressor cylinders, a piston structure including motorand compressor pistons reciprocable in said second motor and compressorcylinders, a double-armed rocker pivoted on a stationary axis midwaybetween said `first and-said second motor and compressor cylinders, andconnections between each arm of said rocker and one of said pistonstructures including connecting rods connected pivotally t-o saidpistons and to said arms respectively.

16. A motoncompressor of the type described comprising, in combination,lirst aligned motor and compressor cylinders, second aligned motor andcompressor cylinders arranged parallel to the first cylinders, a pistonstructure including motor and compressor Pistons reciprocable in saidrst motor and compressor cylinders, a piston structure including motorand compressor pistons reciprocable in said second motor and compressorcylinders, a double-armed rocker pivoted on an axis between said iirstand said second motor and compressor 'cylinders, and connections betweeneach arm of said rocker and one of said piston structures includingconnecting rods one housed in each piston structure and Yeach pivotallyconnected to a piston structure and to a rocker.

v17. In combination, a pair of parallel cylinders, a pair of pistonsmovable in opposition in each of said cylinders, separate means yforconnecting a piston in one cylin- `der for movement in alternation witha piston in the other cylinder, means for synchronizing the movementslof said separate means whereby the pistons in each cylinder move inopposition, said latter means during its operation assuming positions ofunbalance, and counter- Vweight means operatively associated with saidsynchronizing means automatically for oisetting such condition 'ofunbalance thereby to assure smooth relatively vibrationless operation ofsaid pistons.

1S. A combination as set forth in claim 17 wherein said synchronizingmeans includes gear elements rotata- 'ble with each pair ofalternatively moving pistons, and

rack means engaging both gear elements, said rack means engaging therelatively opposite sides of said gear elements.

19. A combination as set forth in claim 18 wherein -said counterweightmeans includes oppositely moving and a linear reciprocable memberengaging said connecting means on opposite sides of the plane in whichthe axes lie about which such oscillations occur, respectively, tosynchronize such oscillation in opposed equiangular relationship.

21. In combination, at least two spaced elongated power cylinders eachof which has a pair of opposed reciprocable pistons therein, spacedconnecting means connecting each one of said pistons of one of saidpairs of pistons to separate pistons of the other of sad pairs ofpistons to obtain movement away from one another of one pair of saidpis-tons upon movement toward one another of the other pair of saidpistons whereby each of said connecting means has an oscillatorymovement, means secured to said oscillating connecting means,respectively, s-o as to oscillate therewith, and a linearly reciprocablelink engaging each of said last mentioned means on opposite sides of theplane in which the axes lie about which said oscillation occurs,respectively, to synchronize such oscillation in opposed equiangularrelationship.

22. In combination, a pair of parallel cylinders, a pair off pistonsmovable in opposition in each of said cylinders, separate means forconnecting a piston in one cylinder for movement in alternation with apiston in the other cylinder, and interconnecting means forsynchronizing the movements of said separate means whereby the pistonsin each cylinder move in opposition, said interconnecting meanscomprising elements connected to each of said separate means and bodilyshiftable means interconnecting and moving relative to said elements.

23. A combination as set forth in claim 22 wherein said bodily shiftablemeans creates conditions of unbalance and cooperating bodily shiftablemeans acting in opposition to said rst mentioned shiftable meanscounteracting said conditions of unbalance.

References Cited in the lile of this patent UNITED STATES PATENTS2,027,877 Pescara Jan. 14, 1936 2,028,331 Janicke Ian. 21, 19362,755,988 Wachsmuth July 24, 1956 2,775,398 Wachsmuth Dec. 25, 19562,800,270 Petersen July 23, 1957

